The present invention relates to a profile measurement apparatus for measuring the thickness of a strip such as a rolled steel sheet by using radiation.
One of the most significant factors in the manufacture of a high-quality rolled steel sheet (strip) is controlling the thickness thereof to be uniform when the rolled steel sheet is continuously manufactured by a rolling mill or a reduction roll. For this reason, a high-speed measuring technique for continuously and accurately measuring the thickness of the produced strip is required to control the thickness of the strip to be uniform.
A conventional strip profile measurement apparatus (profile meter) using radiation comprises both a stationary profile detector for detecting a thickness at the central portion (of the width) of the rolled steel sheet moving linearly in one direction, and a movable profile detector for reciprocating along the width of the rolled steel sheet in a zigzag manner and for scanning its surface. Based on data obtained from the two types of detectors, the thickness of the rolled steel sheet over the entire area is approximated. When an undesirable variation in thickness of the rolled steel sheet is detected, the rolling operation of the reduction roll can be immediately adjusted on the basis of the detection data.
In the conventional profile meter of the type described above, since reciprocal movement of the movable profile detector in a zigzag manner allows it only to measure a partial region of the strip along a zigzag scanning line, most of the strip portion cannot be measured, often resulting in inaccurate measurement. Furthermore, since the profile detecting speed depends on a response time of the movable profile detector, it takes a relatively long period of time to complete measurement of the thickness of the rolled steel sheet along the entire width of the rolled steel sheet. As a result, thickness or profile measurement cannot be performed at a desired high speed.